Electromechanical switching behavior of individual molecular complexes of Cu and Ni on NaCl-covered Cu(111) and Ag(111)

Hermann Walch (1) , Thomas Leoni (1) , Olivier Guillermet (1) , Véronique Langlais (1) , Andrew Scheuermann (1, 2) , Jacques Bonvoisin (1) , Sebastien Gauthier (1)

1 CEMES-GNS - Groupe NanoSciences
2 UF|Chemistry - Department of Chemistry [Gainesville]

In a combined scanning tunneling microscopy (STM) and noncontact atomic force microscopy (nc-AFM) study, we characterize the reversible switching between two stable states of an organometallic complex, namely, bis-dibenzoylmethanato-copper [Cu(dbm)2] adsorbed on an insulating thin film. The switching is due to the transfer of an electron between the STM tip and the molecule, accompanied by a conformational change, i.e., a transition from a square-planar to a tetrahedral geometry. Evidence is given by STM topography and spectroscopy and nc-AFM electrostatic force measurements. Similar experiments conducted on bisdibenzoylmethanato-nickel [Ni(dbm)2] show that this complex does not switch under comparable experimental conditions. We discuss these findings within the framework of crystal-field theory, stating that the occupation of the d orbitals determines the favored coordination geometry of a complex. Accordingly, only the copper complex can undergo a conformational change that facilitates stable storing of the additional electron.

Mots clés: Nc-AFM; STM tunneling microscopy

Domaines: Physique [physics]; Chimie de coordination

Hermann Walch, Thomas Leoni, Olivier Guillermet, Véronique Langlais, Andrew Scheuermann, et al.. Electromechanical switching behavior of individual molecular complexes of Cu and Ni on NaCl-covered Cu(111) and Ag(111). Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2012, 86 (7), ⟨10.1103/PhysRevB.86.075423⟩. ⟨hal-01738068⟩